Mysterious chronicle (part 30) is a book found only in Daemonheim. It may appear in front of the dungeon-ending ladder after killing the boss monster.

Written in the year 165 of the Fifth Age. Bilrach says the end cannot be far now, he can feel the dark energy around him, draining him. He questions, shouldn't it be empowering him? The voice tells him to stop writing. He asks, has he used up all his power getting that far, or is it ebbing through other means? The voice tells him to push onwards. He knows his master will have the answers, he knows he's still himself. He must listen to the voices and push on.

It seems certain from here that Bilrach was indeed tricked in some way, this whole time, by the voices. In the first chronicle he references them as "My power is as true as the whispers calling", were the whispers what guided him to the castle to begin digging in the first place? He was convinced they were his master, Zamorak, but in an earlier dungeons he's right - if it were Zamorak, then he would have had enough influence in the world to bring himself through without the need of him. Whoever or whatever is/are the owner(s) of the voices, they have plans for Bilrach, some way or another, as they want him to keep going down.

The end cannot be far now, I feel the dark energy around me, draining me: shouldn't it be empowering me? The voice tells me to stop writing. Have I used up all my power getting this far, or is it ebbing through other means? The voice tells me to push onwards. I know my master will have the answers. I'm still myself. I must listen to the voices and push on.

This is the last Chronicle that Bilrach had written and is only 4 years before the current year, of 1 in the Sixth age. This shows how close he made it to the bottom before he stopped writing journals. Thanks to the Nadir saga and Dishonour Among Thieves, we now know he made it to the bottom, and largely succeeded in his goals too.